The water from first rainfalls has a high concentration of dirt that has accumulated over time, which is carried by rain to the collection system, causing damage to its equipment, its components and possibly to the health of those who consume this water.
There are currently several processes to gather and reuse rainwater. In the simplest processes, the first rainwater is collected directly by the cistern, and in other processes, is diverted manually until appearing clean to the naked eye, and then redirected immediately to the point of use.
In places where technology is available, multiple filter models are used which grasp leaves, small animals, and waste in their mesh, which may become dirty and clogged, and therefore unable to fully absorb the water since these systems are not self-cleaning. Other systems, although they are self-cleaning, cause wasting of water because they do not adapt to rain volume. As such, they do not capture the total flow of rainwater.